Neat and orderly arrays for micellar systems have been reported,.sup.1,2 and are structurally based on the original work of Vogtle et al.,.sup.3a who delineated "cascade" construction. The U.S. Pat. Nos. 4,435,548, issued Mar. 6, 1984; 4,507,466, issued Mar. 26, 1985; 4,558,120, issued Dec. 10, 1985; 4,568,737, issued Feb. 4, 1986; 4,587,329; issued May 6, 1986; 4,631,337, issued Dec. 23, 1986; 4,694,064, issued Sep. 15, 1987; and 4,737,550, issued Apr. 12, 1988, all to Tomalia et al., relate to branched polyamidoamines. The polyamidoamines include a plurality of pendent aminoamide moieties exhibiting properties which are related to linear polyamidoamines from which the branched polymers are derived. These compounds can be characterized as high molecular weight, highly-branched, multi-functional molecules possessing a three-dimensional morphology. Synthetic strategies employed for the realization of such "cascade polymers".sup.3b require consideration of diverse factors including the content of the initial core, building blocks, space for molecules, branching numbers, dense packing limits, and desired porosity, as well as other factors..sup.4 The selection of the building blocks govern the type of branching desired from the core molecule, as well as the technology used to attach each successive layer or "tier" of the cascade polymer.
Applicants have developed a novel method of making cascade polymers, especially those providing a unimolecular micelle consisting essentially of alkyl carbon possessing diverse terminal functionality. Such compounds are disclosed in U.S. Pat. No. 5,154,853 (1992) to applicants.
Further developments of the above-described chemistry by applicants have demonstrated that the unimolecular micellar character permits the initial evaluation of the orderliness and chemistry within a series of specifically designed, spherical macromolecules due to covalently bound assemblies of internal reactive sites..sup.5,6 Similar dendritic species have been constructed with amide,.sup.4,7,8 ethereal,.sup.9,10 phosphonium,.sup.11 silicone,.sup.12 germane,.sup.13 and aryl,.sup.14-19 inner linkages and functionalities.
Out of all these systems, however, it has been determined that only three systems thus far created have the potential to undergo specifically located chemical modification within the inner lipophilic regions thereof. When there is actual space within these regions, these lipophilic regions are termed "void regions". The sum of the "void regions" constitutes the total "void volume" of the cascade polymer. The presently known compounds having such inner void regions capable of covalent modification are the hydrocarbon-constructed cascade intermediates possessing specifically located internal substituents or unsaturated centers, e.g., dialkylacetylenic moieties, set forth in the above-captioned patent to applicants (U.S. Pat. No. 5,154,853), those compounds disclosed by Moore and Xu,.sup.19 that possess rigid polyalkyne spacers, or connectors, between branching centers and are thus prone to incomplete chemical transformations, and hence asymmetry, due to steric interactions, and those compounds set forth in the Tomalia patents set forth above which are amino-branched compounds having short linkages between branch points (thus minimizing void volume) and internal bridging trialkyl substituted nitrogen atoms possessing less than pure sp.sup.3 hybridization, making internal nucleophilic substitution difficult.
Applicants have found.sup.6 that the dialkylacetylene moieties of the cascade polymers set forth herein are also specifically located within accessible void regions. Applicants have shown that molecular guest probes, including diphenylhexatriene (DPH), phenol blue (PB), naphthalene, chlortetracycline (CTC), and pinacyanol chloride (PC) can be used as micellar probes to access the infrastructure of such cascade polymers utilizing known chemistry..sup.20-24
Demonstrations of accessibility of void regions to chemical modification has led to the development of the ability to manipulate internal moieties within the spherically symmetrical dendritic macromolecule, after construction, to allow easy incorporation of internally located sensitive and/or reactive groups which otherwise would be difficult to introduce or protect during cascade construction. Specifically, the introduction of metal and metalloid centers at the interior of cascade infrastructures has been accomplished. Such derived compounds; referred to generically as metallospheres, superclusters, unimolecular Metallomicellanes and Nonmetallomicellanes, Metalloidomicellanes, derivatized Micellanes, or Micellanes, can be utilized for drug delivery of various metals and nonmetals, which are presently difficult to deliver in pharmacologically efficacious matters. The use of carrier-metal combinations as pharmacotherapeutic agents has had the problem of not being able to deliver sufficient metal/nonmetal to a site at a sufficiently low dose of the carrier of the metal/nonmetal per se.
For example, the U.S. Pat. No. 5,422,379 to Applicants provides a means of delivering high concentrations of the metal/nonmetal moiety(ies) to a site at a relatively low dose of carrier (Micellane system).
Accessibility to void regions can be achieved by various means. Accessibility can be achieved during synthesis of tiers of the macro-molecular or can be achieved after synthesis by various manipulations of the molecule. It has been found that these manipulations of the molecule can be achieved by increasing and then, decreasing the size of the molecule.
A further and most significant step has been taken towards specificity in the access of guest molecules to the void regions and binding of the guest therein. Specifically, a "lock and key" concept has been developed pertaining to unimolecular micelles which takes advantage of several demonstrated and unique characteristics of these cascade macro-molecules. The advantageous characteristics include: (1) the internal, constructed, and predetermined or predesigned void domain(s) created within the micelle superstructure, (2) the ability to gain facile access to these inner void regions with molecular guest(s) to generate a micellar complex and possibly multimicellar complexes comprised of one or more hosts with one or more guests, (3) the ability to incorporate specific acceptor moieties into the structure of one or more arms, branches, or cascade building blocks or the synthetic activation of a dormant, or masked acceptor loci thereby affixing the acceptor moieties permanently, or for a controlled period of time, and (4) the unique homogenous structure and topology of the building blocks which allow the incorporation of predesigned acceptor moieties onto one or more of the unimolecular micelle branches. In other words, an acceptor region which will bind specifically to a complementary moiety can be engineered per se and then specifically disposed and preferentially exposed to the complementary moiety for irreversible or reversible binding thereto. Further, the micellar structure can contain an otherwise soluble receptor (acceptor region) and render the receptor soluble by virtue of soluble components on the micelle surface.
Utilizing these molecules, the present invention can provide for molecular recognition and binding in and between two or more micelles. This is specific binding of a key micelle with a lock micelle, the binding being selective as well as being able to be turned on and turned off.